This invention relates to a corrosion inhibiting composition. In a more particular aspect, this invention concerns itself with a water soluble composition to be added to a water-coolant system used to cool equipment operating at elevated temperatures. The corrosion inhibiting composition of this invention is especially useful in high energy laser operations to inhibit the corrosion of molybdenum laser mirrors which come in contact with the water of the laser cooling system.
A recent analysis of laser mirror systems indicated that their failure, or near failure, is due to the degradative effects resulting from their exposure to corrosive contaminants contained in the water used to cool the mirrors. Water cooled molybdenum mirrors, which are used in high energy laser systems, are especially susceptible to corrosion which has led to catastrophic failures of the mirror systems.
As a result, a considerable research effort was undertaken in an attempt to provide a means for preventing corrosion of molybdenum high energy laser mirrors. The research effort culminated in a solution to the corrosion problem and the development of the corrosion inhibiting composition of this invention. The composition is composed of a triazole inhibitor, such as benzotriazole, a biocide and a buffering agent, such as benzoic acid. The composition is added to the cooling water utilized in cooling the molybdenum laser mirror. The benzotriazole acts as the inhibiting agent while the benzoic acid prevents biological degradation of the cooling water. The benzoic acid also buffers the cooling water to an acidic pH for optimum inhibitor performance. The composition of this invention has been found to be especially effective in preventing the corrosion of molybdenum metal surfaces and can be used with little or no modification to the molybdenum mirror systems used in high energy lasers.